General Astronomy/Black holes/Introduction

In this chapter, we will explore the nature of the Black Hole, how they come to be, and the history of the theories behind them.

A black hole is an object that has a gravitational field so powerful that nothing, not even radiation or light, can escape. The event horizon is the name given to the figurative surface, within which the gravitational force becomes irresistible. Escape velocity at that surface is equal to the speed of light hence not even light can escape, hence it is rendered invisible. In this way, black holes are undetectable, except by the trail of destruction they leave behind them, or their interaction with proximate objects.

The theory behind black holes designates that, when a certain amount of mass is present in an infinitely small region of space (referred to as a "naked singularity"), all paths through space in 4-dimensions are inwardly curved, forcibly pulling all forms of matter toward the source. Such a dense region of space, the black hole, has been predicted to form either following the collapse of a massive star, or the collision of two neutron stars. The former is, however, said to be by far the more common, considering the rarity of the latter.

Many aspects of the black hole model still pose unanswered questions, and the nature of the black hole remains largely unknown. Numerous theories as to what a black hole looks like, and what exists in the interior have been proposed, and the black hole is a regularly seen element of science fiction. Some even propose that black holes could lead to be gateways to other universes or parallel realities with radically different physical laws.

In the following topic, we'll look at these theories, while exploring what is already known about black holes, as well as the history of the concept of objects with a gravitational field so strong that nothing can escape. We will discuss the properties of the black hole, and the impact these properties have on the surrounding spacetime and the matter around them, and how these properties, as well as the effects they cause, can be exploited in the detection of these invisible monsters. Finally, we'll examine the terrible life of the black hole, from its birth in the blazing remains of a destroyed star to its gradual evaporation. The second type of black hole is called the stellar black hole: It is formed by the gravitational collapse of a massive star. Stellar black holes have masses that range from 3 to several thousands of solar masses. Our Milky Way Galaxy has several stellar mass black holes that are closer to us than the super massive black hole in the region. The third type of black hole is called the Intermediate-mass black holes: Intermediate-mass black holes are found in the center of globular clusters. Astronomers believe that colliding stars may have formed the intermediate mass black holes. The fourth type of black hole is called the Super Massive black holes: Super Massive black holes are found in the center of the Milky Way and other active galaxies. Theoretically a star black hole forms and takes in enormous amounts of matter over the course of years. The other theory is that a cluster of star like black holes forms and then merges into a super massive black hole.